SoF which Vcore did you use?
I tested 3 chips, with SS(about -40C):
two could run SuperPi 32m at 5600MHz with 1.7V and best one could 5700MHz.
With LN2 I killed best chip and tryed another(random from two). Max valid http://valid.canardpc.com/show_oc.php?id=2341144
full pot whit high memory divider. I think these cpu are bad